<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<style>
    *{
        margin: 0px;
    }
    .annu{
        width: 90px;
        height: 50px;
        background-color: aquamarine;
        border: 0px;
        color: aliceblue;
        flex-grow: 1;
        border: 1px solid wheat;
        text-align: center;
    }
    .opp{
        display: flex;
        flex-direction: column;
    }
    span{
        line-height: 45px;
        transition: 1s;
    }
    .annu:hover{
        background-color: rgb(10, 105, 74);
    }
    .annu:hover span{
        padding-right: 20px;
        background-color: rgb(10, 105, 74);
    }
</style>
<body>
    <div class="opp">
        <div class="annu">
            <span>阿牛</span><span>&lt;&lt;</span>
        </div>
    </div>
</body>
</html>